VB.net.How to detect overlaps of features when a new layer is beign added

Hello everyone.. I'm a final year student working currently on a project to detect overlaps of features when new layer/polygon(representing individual parcel points) is been added to the map

I want the application to be like when a shapefile is loaded onto the map, the application should be able to allow users to add another polygon to the same polygon shapefile loaded, while loading onto the shapefile I want it to be able to determine
topological relationship and if there is an overlap it shd also flag the user dat there is an overlap in visual basic(vb.net).

Any Idea please...Its urgent b'cos there is a deadline for submission of work...plse help me....